The effects of crystallite growth and dopant migration on the carbon monoxide sensing characteristics of nanocrystalline tin oxide based sensor materials

被引:73
作者
Davis, SR [1 ]
Chadwick, AV [1 ]
Wright, JD [1 ]
机构
[1] Univ Kent, Sch Phys Sci, Ctr Mat Res, Canterbury CT2 7NR, Kent, England
关键词
D O I
10.1039/a803866j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Tin oxide nanocrystals, both pure and Cu2+ and Fe3+ doped, have been prepared by a sol-gel process. The response of these materials to carbon monoxide in dry air has been investigated as a function of annealing temperature. The growth of the crystallites was monitored by XRPD from room temperature to about 900 degrees C and the response of the material to CO was studied for materials annealed over that temperature range. All of the materials were shown to respond to low concentrations of CO with a narrow peak in sensitivity at an operating temperature of about 200 degrees C. A good response to CO was also observed at an operating temperature of about 400 degrees C. No improvements in selectivity to CO were observed by the addition of either of the cation dopants. The sensitivity to CO was shown to decrease as crystallite size increased. The addition of the metal cation dopants impeded crystallite growth. Our previously reported Cu K-edge and Fe K-edge EXAFS measurements, on the Cu2+ and Fe3+ doped materials respectively, showed the dopant cations to move from ordered Sn4+ substitutional lattice sites in the as-prepared materials to more disordered regions, most likely the surface regions, as the materials were annealed. This dopant migration begins at about 400 degrees C and is accompanied by a corresponding large decrease in response to CO at an operating temperature of about 200 degrees C (the peak in sensitivity). This is attributed to the migration of the dopants to the surface of the crystallites and speculative explanations are given. The reduction in response of the same materials at an operating temperature of about 400 degrees C is not so large, indicating the response mechanisms at 200 and 400 degrees C to be different.
引用
收藏
页码:2065 / 2071
页数:7
相关论文
共 27 条
  • [21] IMPROVEMENT OF COPPER OXIDE-TIN OXIDE SENSOR FOR DILUTE HYDROGEN-SULFIDE
    MAEKAWA, T
    TAMAKI, J
    MIURA, N
    YAMAZOE, N
    [J]. JOURNAL OF MATERIALS CHEMISTRY, 1994, 4 (08) : 1259 - 1262
  • [22] CHARACTERIZATION OF CU(II) SITES IN CU/SNO2 CATALYSTS BY ELECTRON-SPIN ECHO ENVELOPE MODULATION SPECTROSCOPY
    MATAR, K
    ZHAO, DY
    GOLDFARB, D
    AZELEE, W
    DANIEL, W
    HARRISON, PG
    [J]. JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (24) : 9966 - 9973
  • [23] TIN DIOXIDE GAS SENSORS .1. ASPECTS OF THE SURFACE-CHEMISTRY REVEALED BY ELECTRICAL CONDUCTANCE VARIATIONS
    MCALEER, JF
    MOSELEY, PT
    NORRIS, JOW
    WILLIAMS, DE
    [J]. JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1987, 83 : 1323 - 1346
  • [24] EFFECT OF ELECTRODE MATERIAL ON SENSOR RESPONSE
    MISHRA, VN
    AGARWAL, RP
    [J]. SENSORS AND ACTUATORS B-CHEMICAL, 1994, 22 (02) : 121 - 125
  • [25] Williams D.E., 1987, SOLID STATE GAS SENS, P71
  • [26] GRAIN-SIZE EFFECTS ON GAS SENSITIVITY OF POROUS SNO2-BASED ELEMENTS
    XU, CN
    TAMAKI, J
    MIURA, N
    YAMAZOE, N
    [J]. SENSORS AND ACTUATORS B-CHEMICAL, 1991, 3 (02) : 147 - 155
  • [27] CORRELATION BETWEEN GAS SENSITIVITY AND CRYSTALLITE SIZE IN POROUS SNO2-BASED SENSORS
    XU, CN
    TAMAKI, J
    MIURA, N
    YAMAZOE, N
    [J]. CHEMISTRY LETTERS, 1990, (03) : 441 - 444